Abstract

The damage and transmission properties of selected commercially available fused silica fibers have been measured as a function of excimer laser wavelength. Two-photon absorption and color center formation in fused silica currently limit the use of these fibers at the excimer wavelengths of 193 nm (ArF) and 248 nm (KrF).

Small signal attenuation coefficients of the all-silica Diaguide ST-U fibers as a function of excimer laser wavelength. The measured attenuation varies approximately as λ−5 as shown by the solid curve. The dashed curve represents the contribution of Rayleigh scattering to the attenuation coefficient, while the curve (– - –) is the prediction from Ref. 20 for the combined contribution of Rayleigh scattering plus the UV absorption edge.

Nonlinear transmission of l = 0.62-m ○ and l = 3.5-m △ 400-μm core diam Diaguide ST-U fibers at the KrF (248-nm) wavelength. The transmission includes Fresnel losses at each end of the fiber, and the input intensity is that which is incident on the fiber. The solid curves represent the theoretical predictions of the nonlinear absorption model.

(a) KrF optical waveform at the input of the l = 3.5-m fiber, (b) transmitted laser pulse for an input peak intensity of 47 MW/cm2. The dashed curve represents the prediction for the transmitted waveform using the nonlinear absorption model.

Dependence of the induced bulk attenuation on the type of fiber. The l = 0.62-m fibers were run in using a KrF laser fluence of 2.7 J/cm2. The low signal fiber transmissions have been normalized using the transmission data obtained on a virgin fiber.